Potentiometer tandem assembly



March 10, 1953 K. w. LINDSAY ET AL POTENTIOMETER TANDEM ASSEMBLY Filed July 24, 1952 2 SHEETS-SHEET l 84 -/a i a M ea l l- 5 i a .1.

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le /WE 7H L/A/DSAY Y EDW/ V DREW/7' March 10, 1953 w, LINDSAY ET AL 2,631,212

POTENTIOMETER TANDEM ASSEMBLY Filed July 24, 1952 2 SHEETS-SHEET 2 wn a4 7 7? 60 V z 76 INVENTORS. KENNETH w. LINDSAY EDW/N DREW/7'2 14 TTOQ/VEYS Patented Mar. 10, 195 3 2,631,212 POTENTIOMETER TANDEM ASSEMBLY Kenneth William Lindsay, Great Neck, and Edwin Drewitz, Flushing, N. Y., assignors to Dejur- Amsco Corporation, Long Island City, N. Y.,'a

corporation of New York Application July24, 1952, Seria1'N0.'300,61 8

2 Claims. 1

This invention relates to a potentiometer tandem assembly and more particularly to the combination of a potentiometer and a second electrical instrument such, for example, as a switch, assembled in tandem relation with mechanical and cooperative electrical precision.

The potentiometer tandem assembly of the present invention pertains in its particular embodiment to a tandem assembled potentiometer and switch in which the movable element of the potentiometer and the movable element of the switch associated instrument are manually rotatable unitarily in either direction from a neutral potentiometer position, and which upon manual release are automatically-returned to such neutral potentiometer position.

Such potentiometer and'switch assemblies are employed in radio and radar circuits which require initial precision operation and repeated unerring reproduceable performance. To accomplish this, the following are two desiderata, both of which are prime objects of the present invention, one being concerned with the manufacture of the assembly and the other with its use:

1. The potentiometer instrument and the associated electrical instrument such as the switch should be so assembl'abl'e tandem, that mechanically (apart from any of the usual electrical tests made subsequently on the assembly), they become coupled in the act of mechanical assembly, even though produced on a mass production basis, with an exact mutual relationship with a high degree of precision, and

2. The potentiometer instrument and the associated electrical instrument in use should maintain with exactitiide the desired precision relationship therebetweenan'dshould be capable after each of the repeatedoperations, of automatically returning the operated parts with continued reliability to their mutual relationship within the closest tolerances.

To the accomplishment of these objects the present invention relates to the potentiometer tandem assembly as particularly defined in the appended claims taken together with the following specifications and the accompanying drawings in which:

Fig. 1 is a side view 'o'f'the potentiometer tandem assembly in its completed form, the parts being shown in the potentiometer neutral position.

Fig. 2 is a rear 'elevationa'lview thereof.

Fig. 3 is a view thereofftaken in cross-section in the plane of line 3 3 of Fig.1.

Fig. 4 is a side*elevationar'view taken entire side opposite to that of Fig. 1, with parts of the potentiometer broken away.

Fig. 5 is 'a partial view thereof showing the essential'parts of the mechanism for coupling the potentiometer and the switch instrument, the same being a view taken in cross-section in the plane of the line 5-5 of Fig. 4 and showing the parts in the same relative relation as they are shown in Fig. 4.

Fig. 6 is a view similar to Fig. '5 showing the position that the parts assume when the poten'-- tiometer shaft is rotated in the direction shown by the arrows in this figure.

Fig. '1 is a view similar to Fig. 6' and showin the position that the parts assume when the potentiometer shaft is rotated in the opposite direction, and

Fig. 8 is an exploded view of the parts employed for coupling the potentiometer and the second electrical instrument, namely, the switch.

Having reference first to-Fig. 1 of the drawings the tandem potentiometer assembly of the present invention comprises a potentiometer, generally designated as P, of known construction and a second electrical instrument coupled in tandem thereto such, for example, as 'a switch mechanism S, which also may be of known construction, and mechanism generally designated as -M mechanically coupling the potentiometer and the switch mechanism to enable precise assembly and electrical cooperation therebetween.

The potentiometer P comprises a casing 0 con-- taining the potentiometer elements, the casing comprising, for example, a cylindrical housing It) provided with an integral front l2 made in the form of an insulating plastic unit, the said housing being provided at its outer end with a metal cover plate I4 and at its inner end with a metal closure plate fl t, the said plates being secured together and to the casing by means of the diametrically positioned bolts l8, 18. The front plate It has riveted thereto a spacer post 28 provided at its front end with a threaded portion 22 for instrument "mountin purposes. The

casing c houses-the potentiometer elements which consist of a fixed loopipotentiometer coil 24 having a pair of sections 26 and 28 (see Fig. 2) and a rotatable contact unit comprising the contact element 39 movable over the range of the resistance element of the potentiometer, said contact element being attached to a rotatable hub 32 clamped to, but insulated from, an operating shaft 34. The potentiometer coil is united mechanically to the casing c'by means of two riveted terminals 36 and '33 which at the same time are connected conductively to the terminal leads of the potentiometer sections. The hub 32 rides over and makes electrical contact with a metal arm 4E riveted at @2 to the front or base of the housing I and riveted at its front end to the potentiometer common terminal at and mechanically to the housing l6. Potentiometers of this construction are of standard or known make. The potentiometer sections 26 and 28 are separated by a neutral area 11. and it will be noted in Fig. 3 of the drawings that the engaging region of the contact element 30 is located precisely at the mid-line of this neutral area.

The second electrical instrument which is united in tandem to the potentiometer and which is here illustrated as a switch mechanism S comprises a support or holder in the form of a plate 46 made of insulating material and designed to carry or have attached thereto two or more fixed switch elements, two of which, as and 5d, are shown in the drawings (seej particularly Fig.2), these elements being riveted to the holder plate 46. Mounted centrally on the plate 36 is the rotatable switch member which comprises a metal annulus 52 secured to a wafer 5 made of an insulating material having a squared central opening 58 to fit over and to be anchored to a squared section 58 formed at the inner end of the shaft 34. The metal annulus 52 is formed with a contact blade section 60 which in Fig. 2 is shown to bridge and to make contact with the fixed switch contacts 48 and 5%. This type of switch mechanism is also of a standard or known construction. It will be apparent that upon rotation of the shaft 3 5, the switch blade 68 may be moved into and out of mating or bridging relation with the fixed contacts 53 and 50 and may be made to make or break contact with any of the fixed elements which are mounted on the switch support or holder at.

As a factor in producing a tandem assembly which is capable of the precision assembling steps and precision maintenance in use, the switch instrument S is directly united to a part of the potentiometer unit. The switch holder or plate 46 is therefore directly assembled to two spacer posts 62 and 8 which are riveted at their inner sides to the potentiometer cover plate IS, the switch holder or plate being attached to the spacer posts at their other ends by any suitable securing means such as by the nuts As aforesaid, tandem potentiometer and switch assemblies of the type thus far described are employed in radio and radar circuits which require initial precision operation and repeated unerring reproduceable performance, these requirements being satisfied by two desiderata which essentially are that (1) the tandem instruments should be so assembled, that mechanically they become coupled in the act of mechanical assembly with an exact mutual relationship with a high degree of precision and (2) the tandem connected instruments should maintain, with exactitude, the desired precision relationship therebetween and should be capable, where designed for automatic return of the parts, of automatically returning the operated parts with continued reliability as to their mutual relationship within the closest tolerances.

These ends are accomplished by the invented construction of the coupling mechanism M. The cover plate It is provided integrally (the same being riveted to the cover plate) with a pin 68 projecting outwardly from said closure element and defining a precise reference point in relation to the neutral area n of the potentiometer. Received by the squared portion 58 of the operating shaft 3 3 is a member in the form of a drive plate Hi rotated by the shaft 34 which drive plate is provided with a fixed pin 12 projecting inwardly thereof and movable '(when the shaft is moved) over and into and out of registry with said fixed reference pin 68, the same being shown in registry position in Figs. 1, 4 and 5 of the drawings. Mounted on the round portion of the shaft 34 and loosely rotatable thereon at its tandem portion are two members M and Hi, the member M being provided with a finger l8 and the member 16 with a finger 83, the finger '18 being arranged to engage one side and the finger being arranged to engage the opposite side of the movable pin 12, and each finger being adapted to be brought into corresponding engagement with the reference pin 68. The members "M and "it comprise, specifically, arm plates having the fingers upturned therefrom, the arm plates being also formed with upturned anchoring fingers 532, 88. These members or arm plates it and 16 are connected by means of a coil spring 86 the ends of which are anchored to the anchoring fingers 32 and t4, the said coil spring being extended about a shaft spacer hub 83, the said spring connecting said members 74 and It in a direction to urge engagement of the fingers 18 and ac thereof with the pins 68 and 12 to bring the latter into registry.

The construction of this coupling mechanism M, its functioning in the assembly and the operation of the parts resulting therefrom, are best depicted in Figs. 5 to 8 0f the drawings. In Fig. 8 these parts are shown in exploded condition, the parts in superposed relation indicating the manner in which these parts are assembled. Fig. 5 shows the parts of this mechanism in the normal or manual released condition. The spring is normally (Fig; 5) under initial tension, of approximately one pound, the coils of the spring being wound tight. In this normal position, the fingers of the plate arms l4 and it, under the influence of the tension of the spring 86 are active on the pin E2 of the drive plate 70 and have moved the same in exact registry over the fixed reference pin 6%. It will now be seen, first, how this construction ensures the assembling of the parts of the instrument with exactitude. The potentiometer elements are in a closed casing all forming a unit, the potentiometer elements of which are not visible to the assembler when the tandem instrument is to be united thereto. The reference pin 68 is, of course, in fixed relation to the inclosed potentiometer elements and has a determined relation with reference to, say, the midline of the neutral area 11. of the potentiometer coil. As a result the drive plate Hi, keyed to the squared tandem portion 53 of the operating shaft 34 has its pin 12 so located thereon that when the two pins 68 and it are brought into exact registry in the manner shown in Fig. 5 of the drawings, the contact element of the potentiometer is at the exact mid-- cealed in the potentiometer casing, brings about that exactitude of the relationship of the parts referred to.

Fig. 6 portrays the operation of the instrument when the shaft is rotated in the direction shown by the arrows in this figure. Fig. 7 illustrates the operation when the shaft is rotated in the reverse direction. In the former case, the pin 12 of the drive plate 10 moves the arm 16 to place the spring 86 under increased tension; and in the latter case, the drive pin 12 moves the arm 14 to similarly place the spring under increased tension. When, in either case, the shaft is manually released, the arm plate, resiliently active on the drive plate, will move the same and return back into pin registry position and will thus return the shaft, even after continuous and repeated operations in use, to the initial potentiometer and switch positions referred to and as are portrayed in Figs. 3 and 2 respectively.

The construction of the tandem instrument, the manner of assembling the same, the use of this instrument and the advantages thereof in manufacture and service are believed to be fully apparent from the above detailed description thereof. It will be further apparent that changes may be made therein, within the purview of the essence of the invention described without departing from the spirit of the invention defined in the claims which follow.

We claim:

1. In a tandem potentiometer assembly, con-= sisting of a potentiometer comprising a closed casing having an inner end plate as its closure element, a fixed resistance element mounted in said casing having resistance sections separated by a neutral area, a contact element rotatably mounted in said casing movable over the range of said resistance elements, a shaft fixed to said contact element for rotating the same, said shaft having an operating portion extending from said casin at its outer end and a tandem portion extending from said casin at its inner closure plate end, and a second electrical device assembled in tandem to said potentiometer and comprising an electrical element fixedly mounted to said closure plate and a mating electrical element fixed to the tandem extending portion of said shaft to rotate therewith, the improvement comprising mechanism mechanically coupling the potentiometer and the electrical device for precise assembly and electrical cooperation therebetween comprising a fixed pin projecting outwardly from said closure element and defining a precise reference point in relation to the neutral area of said resistance element, a member fixed to the tandem portion of the shaft and rotatable therewith provided with a fixed pin projecting inwardly thereof and movable over and into and out of registry with said fixed reference pin, a pair of members loosely rotatable on the tandem portion of the shaft each provided with a finger, one finger being arranged to engage one side and the other finger being arranged to engage the opposite side of said rotatable pin, and

each finger being adapted to be brought into corresponding engagement with said reference pin, and a spring connecting said members in a direction to urge engagement of the fingers thereof with said pins to bring the latter into registry, the said fixed reference pin acting as a stop for both members with the pins in registry and acting as a stop for either one of the members when the other one of the members is moved out of registry by the rotation of the shaft, the said spring acting to automatically return all the moving parts to the potentiometer neutral position.

2. In a tandem potentiometer assembly, consisting of a potentiometer comprising a closed casing having an inner end plate as its closure element, a fixed resistance element mounted in said casing having resistance sections separated by a neutral area, a contact element rotatably mounted in said casing movable over the range of said resistance elements, a shaft fixed to said contact element for rotating the same, said shaft having an operating portion extending from said casing at its outer end and a tandem portion extending from said casing at its inner closure plate end, and a switch device assembled in tandem to said potentiometer and comprising a contact element fixedly mounted directly to said closure plate and a mating contact element fixed to the tandem extending portion of said shaft to rotate therewith, the improvement comprising mechanism mechanically coupling the potentiometer and the switch device for precise assembly and electrical cooperation therebetween comprising a fixed pin projecting outwardly from said closure element and defining a precise reference point in relation to the neutral area of said resistance element, a member fixed to the tandem portion of the shaft and rotatable therewith provided with a fixed pin projecting inwardly thereof and movable over and into and out of registry with said fixed reference pin, a, pair of members loosely rotatable on the tandem portion of the shaft each provided with a finger, one finger being arranged to engage one side and the other finger being arranged to engage the opposite side of said rotatable pin, and each finger being adapted to be brought into corresponding engagement with said reference pin, and a tension spring under initial tension connecting said members in a direction to urge engagement of the fingers thereof with said pins to bring the latter into registry, the said fixed reference pin acting as a stop for both members with the pins in registry and acting as a stop for either one of the members when the other one of the members is moved out of registry by the rotation of the shaft, the said spring acting to automatically return all the moving parts to the potentiometer neutral position.

KENNETH WILLIAM LINDSAY. EDWIN DREWITZ.

No references cited. 

